netdev - Re: [PATCH net-next 02/15] net: sparx5: add indirection layer to register macros

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241002080738.w5qzwndzmoansccx@DEN-DL-M70577>
Date: Wed, 2 Oct 2024 08:07:38 +0000
From: Daniel Machon <daniel.machon@...rochip.com>
To: Jacob Keller <jacob.e.keller@...el.com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Lars Povlsen <lars.povlsen@...rochip.com>, "Steen
 Hegelund" <Steen.Hegelund@...rochip.com>, <horatiu.vultur@...rochip.com>,
	<jensemil.schulzostergaard@...rochip.com>, <UNGLinuxDriver@...rochip.com>,
	Richard Cochran <richardcochran@...il.com>, <horms@...nel.org>,
	<justinstitt@...gle.com>, <gal@...dia.com>, <aakash.r.menon@...il.com>,
	<netdev@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 02/15] net: sparx5: add indirection layer to
 register macros

> > +/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
> > +#define spx5_field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
> > +#define spx5_field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
> > +
> 
> FIELD_GET and FIELD_SET have restrictions in place to enforce constant
> mask, which enables strict checks to ensure things fit and determine the
> bit shifts at compile time without ffs.
> 
> Would it make sense for these to exist in <linux/bitfields.h>? I'm not
> sure how common it is to have non-const masks..

There was a patch for this some time ago [1], it got some push-back and
never got in, AFAICS. 

[1] https://patchwork.kernel.org/project/linux-pm/patch/3a54a6703879d10f08cf0275a2a69297ebd2b1d4.1637592133.git.geert+renesas@glider.be/#24611465

/Daniel